This invention relates to a two-way automated communication system referred to as TWACS®; and, more particularly, to the detection of TWACS inbound communication signals transmitted over a sparsely populated power distribution network.
In TWACS parlance, an inbound signal is sent from a remote, customer site to a utility, often in response to an outbound signal sent from the utility to the customer site. TWACS detection of inbound signals has relied upon decoding a stream of data acquired from the time-varying current waveform propagated through the utility's power grid from a medium voltage level distribution substation. Such substations are, for example, 6 kV, 10 kV, 12.47 kV, etc. An inbound signal with its accompanying data is routed current transformers installed the network at appropriate locations and is provided to a TWACS receiver by an inbound signal pickup unit (IPU) at a receiving location.
This method of detection and processing works well and is cost effective for detecting TWACS signals at voltage distribution substations on a power grid having a substantial number of users; this being so because an IPU's cost can be amortized over the several thousand meters installed at customer sites throughout the grid. The same is not true, however, when the network's power grid is sparsely populated; that is, the power distribution system only has a low number of users. This is because the IPU's (or an equivalent device) cost is now too expensive to justify its use, particularly in low voltage distribution networks.
In addressing this problem it has been found that significant cost savings can be realized if TWACS inbound communication signals are detected in the voltage (rather than the current) domain; this being because only voltage needs to be supplied to signal receiving apparatus at a network substation. This significantly reduces the number of connections required to the utility's power distribution grid and this lowers operating costs.